Influência da pluma aquecida de uma chaminé no escoamento turbulento: uma abordagem inicial via simulação

Large Eddy Simulation (LES) have been employed to investigate turbulent flows. In atmospheric turbulence, this methodology is widely used and, sometimes is complementary to field experiments, leading a more detailed about turbulent flow. In this work a LES model was utilized to describe the influence exerted by a hot plume, emitted for a thermal power-plant in the atmospheric flow in the planetary boundary-layer.A Simulação dos Grandes Turbilhões (LES) é uma técnica amplamente empregada para investigar as propriedades de escoamentos turbulentos. No contexto da turbulência atmosférica, esta técnica complementa estudos experimentais, proporcionando uma descrição espacializada do escoamento. No presente trabalho um modelo LES foi aplicado para avaliar a influência da emissão de uma pluma aquecida por uma chaminé, no escoamento turbulento

A História da Alimentação: balizas historiográficas

Os M. pretenderam traçar um quadro da História da Alimentação, não como um novo ramo epistemológico da disciplina, mas como um campo em desenvolvimento de práticas e atividades especializadas, incluindo pesquisa, formação, publicações, associações, encontros acadêmicos, etc. Um breve relato das condições em que tal campo se assentou faz-se preceder de um panorama dos estudos de alimentação e temas correia tos, em geral, segundo cinco abardagens Ia biológica, a econômica, a social, a cultural e a filosófica!, assim como da identificação das contribuições mais relevantes da Antropologia, Arqueologia, Sociologia e Geografia. A fim de comentar a multiforme e volumosa bibliografia histórica, foi ela organizada segundo critérios morfológicos. A seguir, alguns tópicos importantes mereceram tratamento à parte: a fome, o alimento e o domínio religioso, as descobertas européias e a difusão mundial de alimentos, gosto e gastronomia. O artigo se encerra com um rápido balanço crítico da historiografia brasileira sobre o tema

Multi-instrumental analysis of ozone vertical profile and total column in South America: comparison between subtropical and equatorial latitudes

The behavior of ozone gas (O3) in the atmosphere varies according to the region of the globe. Its formation occurs mainly in the equatorial stratospheric layer, through the photodissociation of molecular oxygen with the aid of the incidence of ultraviolet solar radiation, but the highest concentrations of O3 content are found in regions of high latitudes (poles) through large-scale circulation (Brewer-Dobson circulation). This work presents a multi-instrumental analysis in subtropical (in Santa Maria (SM) – 29.4º S; 53.8º W) and equatorial (in Natal (NT) - 5.4º S; 35.4º W) latitudes of South America, to monitor ozone behavior using O3 vertical profile data (2002–2020) and total column ozone data (1979–2020). Comparisons between latitudes were also analyzed with data from ozonesondes, which have continuous measurements of the vertical ozone profile through the SHADOZ/NASA network, where there is a reference station in Natal. For this, 19 years of data were analyzed using SABER and SHADOZ data for NT, through the monthly average series of each instrument the monthly climatological behavior for the NT station was identified, analysis of percentage and relative differences that showed a good agreement between both instruments, mainly above 20 km altitude. It was possible to identify with the analysis in the lower stratosphere (below 20 km), the ozone content is not correctly represented by the TIMED/SABER satellite. The differences between the latitudes presented interesting analyzes regarding the O3 content in the SM and NT, through the monthly and climatological average of the SABER instrument. Dynamic and photochemical effects can interfere both with O3 formation and its distribution along higher latitudes, through the Brewer Dobson Circulation (BDC). The total column of ozone (TCO) was used, to analyze the main climatic variability that influence the two sites (SM and NT). The data analyzed here to monitor O3 in the atmosphere is available through satellite and ground-based instruments from 1979 to 2020. The instruments showed good agreement between each other (TOMS/OMI x Dobson for Natal, and TOMS/OMI x Brewer for Santa Maria) in the long-term series of O3 content measurements, in line with previous studies for these latitudes in the TCO analysis. For climate variability, wavelet analysis was used over 42 years. The investigation revealed a significant annual cycle in both data series for SM and NT. Other variability pointed out such as the Quasi-Biennial Oscillation (QBO) with significant influences in NT and less significant in SM. In addition, the solar cycle proved to be important and well established (128 months) in both site (subtropical and equatorial). The two locations presented in this work have significant importance in the behavior of ozone due to their latitudinal differences. Furthermore, few studies show this comparison between latitudes in South America using satellite and terrestrial instruments in the analysis of the behavior of O3 gas. The main motivation of this work is to show how this important trace gas behaves in the atmosphere, at different altitudes, latitudes and with different sources of influence, both for O3 vertical profile analysis with satellite data, as well as for TCO

Measurement report: Influence of the Antarctic Ozone Hole in Southern Brazil: Conceptual model for 42 years of analysis the atmospheric dynamics on ozone

The austral spring in the Southern Hemisphere presents temporary reductions in ozone content mainly in the Antarctic region known as the Antarctic Ozone Hole (AOH). However, studies show an influence in mid-latitude regions, such as southern Brazil, where days with temporary decreases in the total column ozone (TCO) are identified. The main objective of this work is to investigate this influence of AOH on the southern region of Brazil, using data from the TCO and vertical profiles that will help to identify the preferential height at which these decreases occur in southern Brazil, in addition to analyzing the atmospheric dynamic behavior during these events in the period 42 years of data (1979 to 2020). The methodology used comprises the analysis of average daily data of the total column of ozone through ground-based instruments (Brewer Spectrophotometer), satellite data (TOMS and OMI), and to compare reanalysis data from the ECMWF-ERA5, for the identification of events of influence of the AOH on the southern region of Brazil. The analysis of the vertical content of ozone (O3) data from the TIMED/SABER satellite provides daily data from 15 to 110 km in height and has 19 years of O3 profiles available in the period from 2002 to 2020. From this, 102 events were identified that influenced Santa Maria (29.4º S; 53.7º W), in the south of Brazil, with a temporary decrease in the ozone content in the period, where between 24.1–28 km of altitude the more significant reductions in O3 during events. In the dynamic analysis, the stratospheric fields showed an increase in the absolute potential vorticity, mainly in September and October. The conceptual models in the horizontal and vertical section of the atmosphere explain the action of the stratospheric and tropospheric jet during the occurrence of events of decrease in the O3 content in Santa Maria. It was possible to identify the strong influence on the development of these events through the connection of the stratospheric jet (polar vortex) with the tropospheric jets (polar and subtropical jet) at medium and high levels of the atmosphere

Multi-instrumental analysis of ozone vertical profiles and total columns in South America: comparison between subtropical and equatorial latitudes

International audienceThe behavior of ozone gas (O 3 ) in the atmosphere varies according to the region of the globe. Its formation occurs mainly in the tropical stratosphere through the photodissociation of molecular oxygen with the aid of the incidence of ultraviolet solar radiation. Still, the highest concentrations of O 3 content are found in high-latitude regions (poles) due to the Brewer-Dobson circulation, a large-scale circulation that takes place from the tropics to the pole in the winter hemisphere. This work presents a multi-instrumental analysis at two Brazilian sites, a subtropical one (Santa Maria -29.72°S, 53.41°W) and an equatorial one (Natal -5.4°S, 35.4°W), to investigate ozone distributions in terms of vertical profiles (2002-2020) and total abundance in terms of total columns of ozone (1979-2020). The study is based on the use of ground-based and satellite observations. Ozone profiles over Natal, from the ground up to the mesosphere, are obtained by radiosonde experiments (0-30 km) in the framework of the SHADOZ program and by satellite measurements from the SABER instrument (15-60 km). This enabled the construction of a continuous time series for ozone, including monthly values and climatological trends. There is a good agreement between the two measurements in the common observation layer, mainly for altitudes above 20 km. Below 20 km, SABER ozone profiles showed high variability and overestimated ozone mixing ratios by over 50 %. Dynamic and photochemical effects can interfere with O 3 for-mation and distribution along higher latitudes through the Brewer-Dobson circulation. The measurements of the total ozone columns used are in good agreement with each other (TOMS/OMI × Dobson for Natal and TOMS/OMI × Brewer for Santa Maria) in time and space, in line with previous studies for these latitudes. Wavelet analysis was used over 42 years. The investigation revealed a significant annual cycle in both data series for both sites. The study highlighted that the quasi-biennial oscillation (QBO) plays a significant role in the variability of stratospheric ozone at the two study sites -Natal and Santa Maria. The QBO's contribution was found to be stronger at the Equator (Natal) than at the subtropics (Santa Maria). Additionally, the study showed that the 11-year solar cycle also has a significant impact on ozone variability at both locations. Given the study latitudes, the ozone variations observed at the two sites showed different patterns and amounts. Only a limited number of studies have been conducted on stratospheric ozone in South America, particularly in the region between the Equator and the subtropics. The primary aim of this work is to investigate the behavior of stratospheric ozone at various altitudes and latitudes using ground-based and satellite measurements in terms of vertical profiles and total columns of ozone